CN101380235B - A Test System for Animal Foot-Surface Contact Movement Reaction Force - Google Patents

Abstract

The invention relates to a testing method and a system for the surface-contact counterforce of the foot and surface of an animal. The invention belongs to the technology of force measuring. The method includes the following steps: confirming a sensor, the rate capacity and resolving capability of which meet requirements; demarcating the sensor; designing the arrangement form of a force measuring array; designing an animal movement channel formed by the sensor; conducting the animal to pass through a force measuring sensor channel; using a video image and the counterforce data collected in a sensor system for screening the data of the whole sole of the animal acted on the sensor as the effective data. The system includes a sensor array bracket, the force measuring sensor array arranged on the sensor array bracket; the strain signal of the sensor on the array is connected on a computer by a conditioning amplifier. The system also includes a high speed vidicon which realizes synchronous collection with the force measuring data. The system can simultaneously measure the information like the contact counterforce, the contact time and the moving action between each sole of a large geckoand a spider and an attachment surface when the large gecko and the spider move on a horizontal plane, on a vertical plane and on a ceiling.

Description

A Test System for Animal Foot-Surface Contact Movement Reaction Force

technical field

The invention relates to the field of testing of animal kinematics and robot bionics. In particular, it relates to geckos, spiders, beetles and other adhesive animals (referring to animals whose soles can generate adhesive force so that they can move on various surfaces in a 3-dimensional space). Test system for force and real-time image acquisition. And can be used to determine the motion performance of the robot. the

Background technique

Movement is the basic characteristic of animals and the basis of animal predation, escape, reproduction, migration and other behaviors. The locomotor behavior of animals is the result of the interaction between the animal and the environment under the action of internal force (muscle force). The pods living on the ground realize the driving, stabilizing, maneuvering and other motion behaviors through the force interaction between the soles of the feet and the ground (including walls, ceilings and other surfaces for adherent animals). Force testing is an important way to understand the law of animal motion, and the information obtained has important guiding significance for the design of robots, especially wall-climbing robots. the

Animals such as geckos, spiders, and insects have the ability to move in three-dimensional space (Three Dimensional-terrain Obstacle Free-TDOF), and can move on positive, zero, and negative surfaces (the outer normal of the earth is positive, corresponding to the ground, walls, and ceilings). Various surface positions can freely realize various complex movements. At present, people's understanding of the interaction force between foot and surface is not enough. Robots with the same motion capabilities have clear and urgent needs in the fields of search and rescue, exploration, outer space detection, and special reconnaissance. Existing robots of this type still lag far behind animals in locomotion. Revealing the mechanical laws of animal movement can guide the dynamic design of robots and improve the performance of robots. This design embodiment is launched with the test of the 3-dimensional motion reaction force of a large gecko (Gekko gecko) on the ground, wall and ceiling. Gecko is the heaviest (up to 150g, average 70g), fast moving (up to 1.5m/s), strong load-bearing capacity, and is representative. It is a typical animal with three-dimensional space barrier-free movement ability. the

In order to accurately define related concepts, the motion reaction force we refer to here refers to the force measured when a single paw of an animal acts on a single sensor. Inertial reaction refers to the dynamic change of the force acting on the sensor due to the movement of the limbs and the action of the soles of the feet on the load-bearing sheet of the sensor when the animal is on the sensor as a whole. the

The relevant technical backgrounds of the motion reaction force test method, multi-dimensional force sensor, load cell array and test system related to the present invention are discussed as follows. the

Test method for motion inertia force or reaction force:

According to the positioning method of the sensor, it is generally divided into fixed type and follow-up type. The follow-up type refers to the test method in which the sensor is fixedly connected to the moving animal. This method can realize the continuous measurement of motion reaction force with fewer sensors, but it has higher requirements for moving animals. At present, it is mainly designed as a whole with people's shoes, and is used for people's motion reaction force test. It is used for large sensors and limited test accuracy, so it is not suitable for the test of small animal motion reaction force. The fixed type refers to the test method in which the sensor is fixedly connected to the static frame of reference. There are many applications, and it is divided into two methods: the test of a single sensor and the test of a multi-sensor array. Experimental testing methods for individual sensors have been studied as early as 1938. Full et al realized the numericalization of the test in 1995. The test method is to install 4 beam sensors under a large load-bearing surface to measure the 3-dimensional ground reaction force and test animals such as lizards, geckos, and beetles. The inertial force generated when moving on the bearing surface (the inertial force generated by the contact between the sole of the foot and the bearing surface, body movement, etc.). (Journal of Experimental Biology, 1995, 198: 2441-2452). Since all animals are located on the load-bearing sheet of the sensor during the measurement, only the inertial force of the animal's movement process can be measured, and the movement reaction force on the sole of a single foot cannot be obtained. the

Sensor technologies that make up the animal motion reaction force test array:

In addition to meeting the requirements of range and resolution, the sensor must have a high natural frequency to ensure the authenticity of the test results because the action of the animal's paw on the contact surface is an impact force. In order to realize the formation of arrays, the installation and fixation of the sensors should also consider the non-interference. The sensor force range and dynamic performance of Full (JEB, 1995, 198: 2441-2452) are suitable, but the sensor structure is too large to form an array. In 1999, the foot contact force sensor developed by Feng Chia University in Taiwan measured the contact motion reaction force between the sole of the foot and the contact surface during different stages of walking (see: The six-component force sensor forming the loading of the feet of in locomotion, Materials and design, 1999, 20: 237-244), two identical 6-dimensional force sensors are installed on the forefoot and heel of the sole, which are made based on the principle of resistance strain measurement. The elastic body structure is spoke type, and the range of force measurement can be Up to ±1000N. The sensor does not report the dynamic performance, it is intended to be installed on the sole of the human foot, and the measurement range is not suitable for the determination of the reaction force of the animal's movement. The inverted T sensor (CN1912559) proposed by the inventor of this patent has higher natural frequency, measuring range and test accuracy, and can meet the requirement of forming an array to prevent fixed interference between sensors. the

Sensor array technology:

From the classification of the structure of the sensor array, the relationship between the sensor and the array can be divided into integral type and split type, and the surface of the sensor array can be covered or not covered. The dimensionality of the force that the sensor can measure is also an important indicator. In 2006, Heo J S et al. made a 3×3 single-dimensional force sensor array [Tactile sensor arrays using fiber Bragg grating sensors. Sensors and Actuators A, 2006, 126: 312-327] made of a fiber grating system, which can be used to measure skin touch And the distribution of fingertip force, the strain gauge sensor array used to measure the robot fingertip force, the range is 100N, the resolution is 0.1N. The force-measuring array only measures one-dimensional force, and the resolution cannot meet the requirements of the animal motion reaction force test. In 2004, the "flexible three-dimensional force tactile sensor (CN1796954)" developed by the Hefei Institute of Intelligent Machinery, Chinese Academy of Sciences, is a set of 16 three-dimensional force sensors in a 4×4 array. It is made of single crystal silicon material through MEMS technology. The piezoresistive effect realizes the detection of three-dimensional force, and its spatial resolution can reach 5mm, and the minimum resolution is 0.1N. The array is an integral structure, and the resolution cannot meet the requirements of the animal motion reaction force test. It is also inconvenient to change the formation mode of the array. In 2005, "A track and field training information collection and feedback system based on digital track (CN1818569)" by Hefei Institute of Physical Science, Chinese Academy of Sciences. In this invention, a plurality of sensor units are placed between the upper plastic layer and the lower plastic layer for protection. The sensor units are connected by row leads and column leads, placed on the ground as a runway, and measure the contact force and time between the soles of the athlete's feet and the runway. . In 2006, "Robot claw bionic finger surface flexible contact sensor array (CN100999079)" of Hefei Institute of Material Science, Chinese Academy of Sciences. The invention utilizes a miniature air pressure sensor and a miniature soft air bag to form a bionic finger-surface flexible contact sensor. A plurality of miniature air pressure sensors are arranged on the sensor substrate, and the miniature soft airbags with airbag micropores are covered and fixed on the miniature air pressure sensors. The sensor substrate is provided with small holes, and the holes communicate with the reference cavity of the miniature air pressure sensors. It is made into a flexible touch sensor array that can automatically adapt to changes in the external environment. These types of arrays are all covered with a continuous protective layer on the sensor, which cannot obtain the real result of animal motion reaction force. the

In 1998, Goodyear Rubber Tire Company developed the "three-dimensional force pin sensor array (US Patent6536292)", which uses multiple cantilever beam sensors to measure the contact force between the tire texture and the attachment surface, and each sensor is independently installed on the base. , allowing quick replacement of damaged sensors in the array, preventing dust and contamination from affecting measurements. the

Following is the closest prior art with the present invention:

The research on animal motion reaction belongs to the cutting-edge field of multidisciplinary interdisciplinary research. The development of the experimental system requires the inventor to be familiar with the needs of animal motion law research. It also needs to have the comprehensive knowledge of sensor development, force measurement array design and development, data acquisition and image acquisition, etc. There are very few teams and personnel at home and abroad who can carry out this kind of research and development. In 2003, Professor Dai Zhendong proposed a "three-dimensional micro-load force measuring array system (CN1544900)". The system uses L-shaped 3-dimensional force sensors to form a sensor array. Based on semiconductor strain testing technology, the measuring range of the sensor is ±10mN, and the design resolution is 0.1% F.S., that is, 10μN. , beetle, etc.) 3-dimensional contact motion reaction force. This technology is the previous self-owned technology of this motion reaction force test system. It adopts the semiconductor strain test technology, the stability needs to be improved, and the force measurement range cannot adapt to the measurement of the reaction force of larger animals such as geckos. The debugging of the sensor array is complicated, and it is difficult to form a variety of array forms with different requirements. the

Contents of the invention

The present invention proposes a set of methods suitable for testing the contact motion reaction force between the paw and the surface when animals move freely on various surfaces without obstacles in 3-dimensional space. It is a sports behavior and mechanics test and analysis system that combines the test of mechanical quantity with sports behavior and gait. To meet the needs of people to explore the laws of animal motion, this research will inspire the design of bionic robots (especially robots with 3D space barrier-free movement capabilities such as imitation geckos). The system can also be used to test the ground reaction force of animals that only move on the ground (such as cats, dogs, etc.). the

A kind of test method of animal foot-face contact motion reaction force, realizes the test to the contact motion reaction force of freely moving animal on various surfaces, is characterized in that comprising the following steps:

Step 1: Select a 3-dimensional sensor with a large range to measure the animal’s movement reaction force under various surface free movement states. After multiple measurements, select the measured maximum load to determine the animal’s movement reaction force experiment. The measuring range of the sensor;

Step 2: Select a 3D sensor that satisfies the above-mentioned measuring range, measure the movement reaction force of the animal in various surface free movement states, and check whether there is a characteristic load (such as preload) through multiple measurements, and use it to determine the The resolution of the sensor of this animal motion reaction force experiment;

Step 3: Design and develop the sensor according to Step 1 and Step 2, and perform online calibration;

Step 4: Observe the movement behavior of the animal, and design the layout of the corresponding force-measuring array, so as to simulate the animal's different spatial positions on the horizontal ground, vertical walls, ceilings, slopes, etc., as well as walking in a straight line, turning, and walls. Transition and other motion states of different traveling modes; the specific layout of the above-mentioned force measurement array is: horizontal "L" type layout, which is suitable for the measurement of the movement reaction force of the animal in the turning state; space vertical "L" type layout, suitable for The movement reaction force is measured in the state of transitional movement between the animal walls; wherein the force sensor array is composed of a plurality of independent force sensors connected with independent load-bearing sheets;

Step 5: Design the channel that guides the animal to pass through the load cell, and train the experimental animal;

Step 6: guide the animal through the force sensor array channel, and use the sensor system to collect the reaction force data, and use the video system to collect the picture of the animal passing through the force sensor array channel;

Step 7: Screen out the data of a single paw of an animal acting on a single sensor from the collected reaction force data as effective data. the

A test system for the reaction force of animal foot-surface contact movement, which is used for testing the reaction force of foot-surface contact movement of freely moving animals on various surfaces. The load cell array on the sensor array bracket, the load cell array is connected to the computer through the signal conditioning amplifier, and also includes a high-speed camera that realizes synchronous acquisition with the force measurement data; The mirror is used to cooperate with the high-speed camera to realize the image acquisition of the back and the side when the animal is moving; the force sensor array is composed of a plurality of independent force sensors connected with independent force bearing plates, and each independent force sensor as a whole becomes an inverted "T"-shaped structure, including vertical beams and horizontal beams, the upper part of the vertical beam has a waist-shaped hole, and the lower part has two "H"-shaped through holes perpendicular to each other in space; there are two "H"-shaped through-holes on the horizontal beam The two holes are symmetrical with respect to the center line of the vertical beam. There are three patch positions on the vertical beam and the horizontal beam, each with a set of metal strain gauges, which are used to measure the three components of the measured force F _X , F _Y , F _Z ; the specific arrangement form of the above-mentioned force measuring array is: the horizontal "L" arrangement form is suitable for the measurement of the movement reaction force of the animal when it turns and moves, and the space vertical "L" arrangement form is suitable for the animal between walls. Movement reaction force measurement during transitional motion states.

In the past, the testing of animal (including human) motion mechanics was mainly carried out on the situation of motion on the ground (so the reaction force is generally called Ground Reaction Force-Ground Reaction Force-GRF). However, animals such as geckos have the ability to move freely in 3-dimensional space on any surface such as the ground, walls, and ceilings. The test of the motion reaction force of this kind of animal on the surface other than the ground has only been seen in the overall test experiment (Journal of Experimental Biology, 2006, 209: 260-27) of the gecko in Autumn on the simulated wall surface, but the test instrument used is still A single beam 3D sensor in 1995. the

Existing force sensor arrays require different backgrounds, some are used for the tactile sense of the palm of a robot, some are used to measure the contact between the wheel and the ground, and some are used to test the reaction force of animal motion. Different requirements place different requirements on the invented test system. The present invention takes the test of the 3-dimensional motion reaction force of the gecko 3-dimensional space (ground, wall, ceiling, etc.) as the background, and the problem itself is brand new, and there is no report on the invention of similar equipment. The existing animal motion reaction force test methods and test systems cannot obtain the relationship between the contact motion reaction force of each foot in animal motion and its change over time (transformation from support phase to moving phase) to understand animal motion mechanics. important information about the law. the

Using this experimental system, we have successfully realized the measurement of the movement reaction force of various small animals. For example, the determination of the reaction force of animals such as geckos, yellow-spotted bugs, and wood frogs. the

Combined with the research of the National Natural Science Foundation of China, we have measured the preload forces of freely moving geckos for the first time. Preload refers to the pressure of the gecko's toes on the contact surface during contact. Foreign studies (Autumn, et al, Nature, 2000) have shown that preload is the basic condition for the generation of adhesion. The test results show that the preload of the gecko is incredibly small, only a few millineww to tens of millineww! And the relationship between preload and motion speed, adhesion force and motion reaction force was determined. This result shows people the very delicate and rich side of the motion reaction force of the giant gecko. Typical curves of motion reaction force versus time are shown in Figure 5. the

Using this system, for the first time, we systematically measured the motion reaction force of the giant gecko on the ground, wall and ceiling. We found that the motion reaction force of the large gecko on the ground, especially the lateral force, is not directed outward on the gecko's feet as predicted by the predecessors. Rather, it is mainly directed inwards. This shows that the gecko's limbs are exerting force to the outside when moving on the ground. We found that the force used by the big gecko for driving is very small, only a few millineww to dozens of millineww, indicating that its movement efficiency is very high. For the first time, we confirmed that the forelimbs are more important than the hindlimbs in the locomotion of the gecko - the forelimbs bear 60% of the body weight, while the hindlimbs only bear 40% of the body weight (Fig. 6). the

Using this system, we measured the movement reaction force of the giant gecko on the ceiling for the first time, and found that at this time, the limbs of the giant gecko actively retracted, forming an in-plane reaction force pointing outward. And the reaction force on the front foot points to the forward direction, and the reaction force on the back foot points to the opposite direction of motion. The resulting adhesive force is slightly greater than the gecko's weight. The individual components of the kinetic reaction force have a very definite direction. The value of each reaction force of the gecko on the ceiling is the largest. the

Using this system, we found that on the wall, the gecko's forelimbs play a major role, generating lateral force, driving force and adhesion force enough to support the gecko's movement, and control the stability and turning behavior of the movement sexual effect. The lateral force and adhesive force generated by the hind limbs are only a few millineww to tens of millineww, which only contribute to the driving force. the

Using this system, we measured the locomotor reaction force of the stinkbug, and found that the locomotor reaction force was as small as hundreds of micronewtons to several millinewtons. the

Description of drawings:

Figure 1A array uses 3-dimensional sensors and their load-bearing sheets; Figure 1B shows the layout and wiring of sensor resistance strain gauges. the

Label name in Fig. 1: 1. Bearing sheet, points 2, 3, and 5 respectively place load-bearing sheets in the front, back, side and normal directions, and points 4 and 6 are used to fix the sensor to the frame On, 7. Sensor elastomer. the

Figure 2. Load cell array for different surface positions. Figure 2A load cell array is in the horizontal position, doing the counter force experiment of animals moving on the ground; Figure 2B load cell array is in the vertical position, doing the counter force experiment of animal moving on the wall; Figure 2C load cell The array is in a downward position, and the reaction force experiment of the animal moving on the ceiling is done; the included angle between the normal direction of the load cell array and the normal direction outside the earth can be realized from 0 to 180 degrees. the

Figure 3. Different arrangements of load cell arrays. Figure 3A is the layout of load cell arrays when animals move along a straight line; Figure 3B is the layout of load cell arrays when animals are turning; Figure 3C is the layout of load cell arrays when animals are transitioning between walls. the

Figure 4. The composition of the animal movement reaction force test system. the

The names of the labels in Fig. 4: 8. Array bracket, 9. Sensor group, 10. Mirror, 11. Signal conditioning and amplifier, 12. Computer, 13. High-speed camera. the

Detailed ways:

In order to further illustrate the technical points of the present invention, the feasibility and implementation effect of the technical scheme proposed in the present invention are shown below in conjunction with the measurement of the gecko motion reaction force. the

Test Methods:

In order to realize the test of the reaction force of the foot-surface contact movement of freely moving animals on various surfaces, we have established the test method as follows in years of research. (1) First, select a 3D sensor with a large range to measure the movement reaction force of the animal under various surface free movement states. Here, the test experiment will be carried out several times (generally greater than 16 times), and the maximum load (peak value) is selected to determine the range of the sensor intended to be used in this animal movement reaction force experiment. (2) Select a sensor with a suitable range to measure the movement reaction force of the animal in various surface free movement states. Here, the test experiment needs to be carried out many times (generally greater than 16 times) to check whether the characteristic load has been measured. For example, when an adherent animal needs to generate an adhesion force, the foot must first apply a normal force. This force is called Preload forces. Used to determine the resolution of the sensor to be used in this animal movement counterforce experiment. (3) The calibration of the sensor is generally carried out by the static weight method or by an electronic balance (the general accuracy reaches 1/10,000). (4) Observing the movement behavior of the animal, and designing the arrangement form of the corresponding force-measuring array. (5) Design and guide animals to pass through the channel of the load cell, and train the experimental animals. (6) Design, process and debug the force sensor array, develop data acquisition software, and realize the synchronization of force acquisition and image acquisition. (7) Find out the result that all the soles of the feet act on the load cell from the reaction force data collected by the video and the experiment. (8) The geometric position of the sensor array system is adjustable, which can simulate the movement state of animals in different spatial positions such as the ground, walls, and ceilings. the

The design of the load cell array should fully consider the following issues:

(1) In the present invention, each sensor can measure three independent force components (Fig. 1A), which can ensure that the measured reaction force is complete without loss of force in a certain direction. According to the circuit principle of the strain sensor, each sensor has 12 (3×4) output lines (Fig. 1B). In the present invention, the output of each sensor is integrated into an independent output connection unit (line connection points D1, D2, D3, D4 in FIG. 1B). The individual outputs form a connection set. Each output unit is connected to an intermediate junction box. The breakout box is connected to the strain signal conditioning and amplifier 11 . The amplified signal is input to the computer through the connection line, and the multi-channel acquisition circuit completes the acquisition of the analog signal and converts it into a numerical signal. In the experiment, the collected numerical signal is displayed on the display screen of the computer, which is convenient for the experimenter to observe. These signals are simultaneously stored to the computer's hard drive for subsequent analysis. In order to obtain the relationship between the movement behavior and the movement reaction force, the movement images of the animals were collected synchronously in the experiment, and the video was automatically triggered by the signal that the animals entered the observation area. The invention can improve the accuracy of the test and ensure the dynamic performance of the test by using an independent sensor without a surface covering. the

(2) The size of the sensor load-bearing sheet (Fig. 1, structural size a×b) is determined. In the present invention, the load-bearing sheet of the sensor should be moderately larger than the size of the paw of the animal to be measured. The purpose is to allow a single foot to step on a load-bearing sheet of the sensor as far as possible, so as to obtain direct force measurement results. the

(3) In order to make the load cell array simulate the rotating device of different surfaces (Fig. 2 illustrates the design of 3 kinds of surfaces and the rotating device. Fig. 2A load cell array is in the horizontal position, doing the reaction force experiment of animals moving on the ground; Figure 2B force sensor array is in the vertical position, doing the reaction force experiment of animals moving on the wall; Figure 2C force sensor array is in the downward position, doing the reaction force experiment of animals moving on the ceiling; force sensor array The angle 0-180 degrees between the normal direction of the earth and the normal direction outside the earth can be realized). Considering that the load cell array can simulate the surface at different positions, a rotating device is designed to simulate any surface position between the ground and the ceiling. When turned to the desired position, the load cell array can be locked with threads to ensure the stability of the position. the

(4) According to the purpose of the experiment, design and determine the arrangement of sensors and the number of sensors (Figure 3, illustrating the arrangement of several sensors. Figure 3A The force sensor array arrangement when the animal moves along a straight line; the movement reaction force measurement of the animal , which is traditionally limited to the determination of the motion state on the plane, here we retain such a basic function, here the length dimension (L) of the load cell array should be greater than the length of one motion cycle of the gecko, and the width of the load cell array should be greater than The distance between the left and right paws of the gecko is to ensure that four paws can act on the sensor, that is, no less than one cycle of motion is collected. Figure 3B The arrangement of the load cell array when the animal turns to move; The load cell array layout form of motion reaction force when turning.The arrangement of the steering area of the sensor here makes the turning radius that it forms should be greater than the turning radius in the actual motion of the animal.The load cell during transitional motion between the animal walls of Fig. 3C array arrangement). Arrangement of load cell arrays for testing transitional motion of animals between planes. Here the number of sensors in plane 1 and plane 2 depends on how the animal transitions. For direct transition, the width (W) should be the same as the width in Figure 3A. If the transition is gradual with one foot on the side, the width (W) should be sufficient to support the entire transition. Arrangement of load cell arrays for the determination of motion reaction forces during the transition between walls

(5) Determine the distance between the sensors and between the sensors and the motion plane according to the magnitude of the force, the stiffness of the sensors and the range of the sensors (d1 and d2 in Fig. 3A, B, C). (5) Avoid interference between sensors. The distance between the sensors (d1 in Fig. 3A, B, C) and the distance between the sensor and the movement plane (d2 in Fig. 3A, B, C) is determined according to the deformation of the sensor under the maximum force of the animal, and a certain amount is reserved. gap. This design has the function of protecting the sensor from damage caused by too much force. the

(6) The sensor is fixed on the frame. In the present invention, the fixing of the sensor is realized by the fixed platform (referring to figure 1 label 6) at its two ends, and is fixed on the frame with screws (referring to figure 1 label 4). Therefore, when designing the load cell array, it is necessary to consider that the fixed part has enough space to avoid interference between the sensor and its fixed part. the

The system composition, related components and connection relationship of the load cell array:

Figure 4 shows the system composition and connection relationship of the load cell array. The components that make up the force sensor array are: 3-dimensional force sensor (1-7), array support 8, sensor group 9, mirror 10, signal conditioning and amplifier 11, connected to the computer through the signal line to complete the data acquisition, force The signal and image acquisition are synchronized through the signal line, and the gait of the animal movement process is collected by a high-speed camera 13, connected and stored in the computer through the signal line. the

The giant gecko has super athletic ability and can move on various surfaces. To illustrate the problem, we choose the ground, wall and ceiling for testing. These surfaces can be defined as positive, zero, and negative surfaces (referring to the analysis of the outer normal of the surface and the direction of the outer normal of the earth in the same direction, perpendicular and opposite) respectively. Any surface is between a positive surface and a negative surface. Therefore the technical scheme shown in this embodiment can be used for the motion reaction force measurement of any surface. the

The system (Fig. 1) consists of a three-dimensional force sensor (CN1912559), which is determined according to the size of the sole area of the gecko. By measuring the body parameters of the gecko, considering the cost and other factors, a load cell array consisting of 2 rows of 8 sensors in each row is formed. The maximum span of the front and rear feet of an adult gecko in motion is about 65 mm, and the distance between the left and right feet is slightly smaller than the maximum span of the front and rear feet. The plane of the load cell array is composed of 16 30mm×30mm plexiglass load-bearing sheets of 3D force sensors. According to the finite element analysis results of the elastic body structure of the 3-dimensional force sensor, under the force of the full scale (1.5N) in the X and Y directions, the displacement of the bearing plate in the X direction is 0.86mm, and the displacement in the Y direction is 0.28mm. The distance between the force-bearing pieces of adjacent sensors forming the array is 1mm, which can ensure that the adjacent force-bearing pieces will not collide under the full-scale force. The channel for animal movement, the position of the force sensor array can be adjusted to simulate the rotation mechanism of the ground, wall and ceiling, the extraction and conditioning of sensor signals, the acquisition of multi-channel signals, the software and hardware required for processing and display, and force signals It is composed of high-speed image acquisition with synchronous acquisition and matching light source system. the

The single three-dimensional small-range force sensor (Fig. 1, CN1912559) used to form the force sensor array becomes an inverted "T" structure as a whole, including vertical beams and horizontal beams. There is a waist-shaped hole on the upper part of the vertical beam (for lightening the elastic body The weight of the sensor reduces the influence of the gravity of the sensor on the measurement results), the lower part has two "H"-shaped through holes perpendicular to each other in space; there are two "H"-shaped through holes on the horizontal beam, and the two holes are opposite to the vertical beam The center line of the elastic body is symmetrical, and a set of metal strain gauges are attached to each of the three patch positions on the elastic body, which are used to measure the three components of the measured force (F _X , F _Y , F _Z ).

Considering that the three-dimensional force sensor will also have small errors or deformations during processing, patching, transportation, and installation, which will affect the installation position of the originally designed load-bearing sheet, an installation position adjustment device is designed to adjust the gap between the sensor load-bearing sheets. The mutual distance, as well as the flatness and spacing between the load-bearing sheet and the plexiglass plate and other parameters. During assembly, each sensor is clamped on a separate fixture. The two ends of the horizontal beam of the sensor are used as clamping parts. The sensor can move in the chute of the fixture to adjust the distance between adjacent sensors in the Y direction. The width of the chute is slightly Greater than the width of the horizontal beam of the sensor, the spacing in the X direction can be fine-tuned through bolts. The fixture is installed on the installation base plate of the sensor array. Due to the individual differences in the size of the large gecko, according to the body width of the large gecko, the distance between the two columns of sensors can be adjusted by moving the clamp in the chute of the installation base plate, so that the soles of the large gecko can just step on it. on the bearing sheet. the

The 3-dimensional force sensor voltage signal acquisition and conditioning hardware adopts the SCXI-1001 chassis of National Instruments. The hardware is installed with 6 SCXI-1520 general strain measurement modules. SCXI-1314 is an external wiring module matching with SCXI-1520. Each SCXI -1520 can realize the signal conditioning of 8 groups of independent bridges. By using a low-pass filter with a cut-off frequency of 100Hz (adjustable) and a stable excitation power supply, the signal-to-noise ratio of the signal can be effectively improved. With the PCI-6052E data acquisition card, in the multiplexing mode, multi-channel can be realized. Synchronous sampling. the

In the large gecko contact movement reaction force synchronous test experiment, the special test program written in the LabVIEW development environment, the experimental test program can be divided into three modules as a whole, namely the start acquisition module, initialization module, and experimental data acquisition and storage module. Set the sampling rate to 1000scans/s, establish 48 virtual channels, and adopt continuous loop acquisition with buffer. Although the coupling between X, Y, and Z of the three-dimensional force sensor is very small, due to the high precision requirements, each sensor is decoupled during the calibration process, and the decoupling matrix is written into the test program, and the final output is The magnitude of the three directions of force acting on each sensor, and realize the sensor's automatic initialization of zero balance in the program. Use the shift register to set the data queue in the memory. The saved data is the data collected in the first few seconds (adjustable) when the trigger is triggered. After judging the validity of the data, it is decided whether to trigger data collection and storage, which improves the experimental performance. efficiency. the

The contact force of the big gecko's soles has a great relationship with the crawling speed and gait, so it is necessary to observe and take pictures of the big gecko's movement process while measuring the force. In order not to affect the camera, the passage where the giant gecko crawls is made of transparent materials. The light adjustment in the auxiliary camera component is to direct the two strong light sources to the 3D load cell array from a certain angle, and adjust the load cell array through the graphic display on the PC to simulate the positive, zero, and negative surfaces. The position and illumination angle of each strong light source. There are two mirrors on both sides of the 3-dimensional load cell array. The angle between the mirror surface and the plane of the large gecko movement channel is adjustable. Through the adjustment of the mirror angle, the high-speed camera can capture the large gecko motion image in the mirror surface. This is a profile image of the gecko when it is in motion. One side can clearly see the movement status of the two soles on one side of the gecko's body, and two mirrors can observe the status of the four soles of the gecko. Combined with the back image of the gecko's movement directly taken from the front by the high-speed camera, the graphic image of the gecko's movement can be completely observed. the

Considering the crawling speed of the big gecko and the needs of analysis, set the acquisition speed of the high-speed camera to 250 frames per second, save the image in the 4G memory space first, and transfer it to the hard disk of the computer when the test data is judged to be valid, so as to improve the experimental efficiency. Through the image analysis software, while obtaining the adhesion force of the gecko on the force-measuring plane, it is possible to obtain information about the gait, speed, and attachment of the gecko’s feet on various surfaces in the state of motion. Surface contact force and other data. the

The method of using 16 three-dimensional inverted "T" force sensors to form a force sensor array, combined with the real-time recording and processing of dynamic images is very suitable for the study of the gait of the gecko and its contact mechanics. From the measurement data of various static performance indicators of the micro force sensor, the linear measurement range of the sensor is 0-1.5N, the resolution is 1mN, the inter-dimensional coupling is less than 0.15%, and it has good linearity and repeatability. Through the specially developed computer application program, multi-channel data collection, data display and inter-dimensional decoupling processing can be realized, and the magnitude and direction of the contact force at each point can be obtained. The transparent force-measuring plane cooperates with adjustable mirrors on both sides, and uses high-speed camera and image acquisition programs to obtain image data of the gecko's movement gait, and analyze the reasons for changes and fluctuations in mechanical data in a timely manner. The large gecko motion test system based on the three-dimensional force sensor array will lay a solid foundation for the subsequent research on the contact mechanics of the large gecko. the

Due to the relatively large weight of the big gecko, when moving on the positive, zero and negative surfaces, the three directions of F _X , F _y , F _z , may exceed its own weight. Therefore, it is required that the range of each direction of the load cell must be within Above 1.5N. In some motion states, the force value of the large gecko's paw is very small when it contacts the attachment surface, and the magnitude and direction of the force change rapidly, which requires the sensor not only to have a high force resolution, but also to have a good understanding of the dynamics of the sensor. Performance has certain requirements.

When analyzing the coordination mechanism, the contact force of the big gecko’s feet is directly related to the gait characteristics of its movement. Neither the analysis of the force characteristics nor the gait characteristics alone can reveal the inner coordination principle well. The force is synchronized. The contact process between the paws of the big gecko and the attached surface is usually completed in a very short time, and the sampling speed of the general camera CCD cannot meet the experimental requirements. the

Claims (1)

1. the test macro of an animal foot-face contact movement counter-force is used for the test to freely-movable animal foot-face contact movement counter-force on the various surfaces, it is characterized in that comprising:

Force cell array bracket, the force cell array, the force cell array that are installed on the force cell array bracket are connected in computer through the signal condition amplifier, also comprise the high-speed camera of realizing synchronous acquisition with the dynamometry data;

And the mirror of two sides adjustable angle is installed, back and lateral image acquisition when realizing animal movement in force cell array both sides with the cooperation high-speed camera;

Wherein the force cell array is made up of a plurality of independently force cells that are connected with independent load sheet, and each independently force cell integral body become the structure of falling the T-shape, comprise vertical beam and horizontal beam, a mounting hole is arranged at vertical beam top, and two spatially orthogonal " H " type through holes are arranged at the bottom; Two " H " type through holes are arranged on the horizontal beam, and two holes are with respect to the centrage symmetry of vertical beam, and design three place's patch location are respectively posted one group of metal strain plate on vertical beam and the horizontal beam, are respectively applied for measurement by three component F of dynamometry _X, F _Y, F _Z

The concrete arrangement form of above-mentioned force cell array is:

Level " L " type arrangement form is applicable to that described contact movement counter-force is measured under this animal divertical motion state,

Spatial vertical " L " type arrangement form is applicable to described contact movement counter-force measurement under the transient motion state between this animal metope.

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